1. Field of the Invention
The present invention relates to an optical signalling device having a partially transparent envelope, a substantially U-shaped luminous tube containing a gaseous atmosphere being placed within said envelope and supplied by a capacitor which is charged and discharged by means of electric circuits placed on a printed circuit card.
2. Description of the Prior Art
The devices aforesaid are employed for emitting light signals of short duration and high intensity in order to attract the attention of persons at distant locations, and in particular to warn maintenance personnel of the presence or imminence of a danger. These devices usually consist of gas-filled glass tubes which are bent in the shape of a U and have a certain degree of fragility. These tubes have two supply terminals which are on the one hand sealed in the glass and on the other hand electrically connected to a capacitor by means of an electronic circuit arranged on a printed circuit card in which supply voltages of the order of 300 V must be employed in order to charge the capacitor. Moreover, conduction of the luminous tube takes place by excitation of an electrode which is external to the tube and has the function of producing initial ionization of the gas by application of a voltage of several kilovolts.
The application of the components required for generating these voltages as well as the relative fragility of the tube have led a certain number of manufacturers to encapsulate all or part of the circuits concerned in a block of insulating plastic having the ancillary function of providing a mechanical support for the tube.
While producing good results when the materials are suitably chosen, this technique has the disadvantage, however, of being technically costly.
The aim of the present invention is therefore to endow a signalling device having the above-defined structure with improvements which are intended to simplify the manufacturing process while at the same time retaining the desired electrical properties and also providing the gas tube with effective mechanical support without having recourse to coating material.